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Likely Mojave Plague Epizootic Appeared to Involve Both Desert Cottontails and Black-tailed Jackrabbits

Young wild desert cottontail in the Mojave Desert
Research · Disease, parasites & microbiology

A 2026 paper describes what the authors consider a likely plague epizootic involving desert cottontails (Sylvilagus audubonii) and black-tailed jackrabbits (Lepus californicus) in California, USA’s Mojave Desert. The authors present it as the first described plague epizootic from the Mojave and the first such account involving both lagomorph species.

An epizootic is an outbreak of disease in an animal population, analogous to an epidemic in humans. Plague is caused by the bacterium Yersinia pestis, which became established in wild mammal communities in western North America after its arrival around 1900. Its ecology is best studied in rodents and their fleas, while much less is known about how plague circulates in rabbits and hares.

The authors describe the event cautiously

The paper says the Mojave event appeared to involve both desert cottontails and black-tailed jackrabbits and therefore labels it a likely epizootic. That wording matters: the report supports plague as the explanation for the event, but the publicly available primary text does not provide enough diagnostic detail to reconstruct the infection status of every individual animal or the complete transmission chain.

A human case of plague also occurred during the event. The paper discusses the public-health implications of plague in lagomorphs, but the available primary text does not establish a specific transmission route from one of the rabbits or hares to the person.

Lagomorphs are a poorly understood part of plague ecology

Most North American plague research has focused on rodents, even though rabbits and hares can also be infected. The authors argue that better understanding infection in lagomorphs matters for both ecosystem health and human exposure because these animals can occur close to people and may participate in local plague cycles in ways that are not yet well described.

They also suggest that plague could be one factor contributing to the broader long-term decline reported in rabbit and hare populations, especially black-tailed jackrabbits. This is presented as a possible ecological link rather than a conclusion demonstrated by the Mojave event itself.

The study therefore adds a new regional and host combination to the known ecology of plague while leaving important questions unresolved: how frequently lagomorphs become infected, how transmission is maintained in desert systems and how much disease contributes to population change.

Sources and image credit

  1. Davis, R. M., & Biggins, D. E. (2026). A likely plague epizootic involving wild lagomorphs in the Mojave Desert of California: Public health and ecological implications. Vector-Borne and Zoonotic Diseases, 26(8), 461–465. https://doi.org/10.1177/15303667261451608Primary peer-reviewed article; PubMed records an article date of 15 May 2026, with later publication in the August issue. The paper describes a likely Mojave plague epizootic involving desert cottontails and black-tailed jackrabbits, including a human plague case.

Image: Jessie Eastland — six-week-old wild desert cottontail exploring the Mojave Desert, photographed 2 June 2015; representative regional image, not an animal from the reported epizootic. Source: Wikimedia Commons. · CC BY-SA 3.0 · Source

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